A substantial hybridization between correlated Ni-d orbital and itinerant electrons in infinite-layer nickelates

The discovery of unconventional superconductivity in hole doped NdNiO 2 , similar to CaCuO 2 , has received enormous attention. However, different from CaCuO 2 , R NiO 2 ( R = Nd, La) has itinerant electrons in the rare-earth spacer layer. Previous studies show that the hybridization between Ni- d_x²-y² d x 2 − y 2 and rare-earth- d orbitals is very weak and thus R NiO 2 is still a promising analog of CaCuO 2 . Here, we perform first-principles calculations to show that the hybridization between Ni- d_x²-y² d x 2 − y 2 orbital and itinerant electrons in R NiO 2 is substantially stronger than previously thought. The dominant hybridization comes from an interstitial- s orbital rather than rare-earth- d orbitals, due to a large inter-cell hopping. Because of the hybridization, Ni local moment is screened by itinerant electrons and the critical U Ni for long-range magnetic ordering is increased. Our work shows that the electronic structure of R NiO 2 is distinct from CaCuO 2 , implying that the observed superconductivity in infinite-layer nickelates does not emerge from a doped Mott insulator.